Hey, I'm new with kde so don't know if this is a basic thing or not.
Either way, I have a Logitech MX Revolution mouse, and the previous/next buttons don't work on dolphin. They do work on the browsers for example, so I'm guessing the mouse is working properly in a general manner.

Any one knows how to fix it?

other question, sort of unrelated, I'm used to clicking ctrl+w to close the folders (in this case, dolphin), anyone knows how to set a keyboard shortcut to target only dolphin?

Open Dolphin > Settings > Configure Shortcuts, find the shortcuts and assign them using your mouse. You may need to follow a guide to get the keys to send appropriate keyboard signals, as found in this forums Tutorials & Tips section.

Found the shortcuts, but it doesn't recognize the mouse buttons.

You're talking about this thread? viewtopic.php?f=14&t=85430

Do I do as it is said and it works with this mouse?

You might have to change b:9 and b:8 to something else, which you can find with xev. More info here: viewtopic.php?f=14&t=82857

Its working, thanks!

In my case, b:9 goes back, and b:8 is for forward.